It is often necessary for fisherman to tie fishhooks to fishing leaders when they are in the field fishing. This may be necessary to replace a hook which was lost, or to simply change the size or type of hook which is being used. This is particularly true in in the case of fly fishermen, since they often change the type of fly which they are using.
It is often difficult for a fisherman to thread a leader through the eye of a fishhook because of the size of the eye and the conditions under which the hook is being threaded. In the case of fly casting, the hooks used for the flies are often very small and have extremely small eyes through which the leader must be threaded. Manually threading a leader through such small eyes requires close attention, very steady hands and good eye sight.
In addition, in the case of a fly which has not been previously attached to a leader, there is very often lacquer used in forming the fly which has spread across the eye of the hook, blocking the eye and preventing passage of the leader through it.
The conditions under which a fisherman is attempting to attach a hook to a leader can affect the fisherman's ability to thread the leader through the eye of the hook. Very often, especially in the case of fly fishermen, the fisherman may be standing on extremely slippery footing, such as in the middle of a stream which would make it very difficult for him to hold the fishhook eye and leader steady.
Because of these reason, it would be advantageous for fishermen to have a threader which would hold the fishhook eye and guide the leader through it. With such a device a fisherman could thread a hook without having to do it through precise positioning of the hook and the leader with his hands.
One attempt to create such a device is shown in U.S. Pat. No. 2,682,126 to E. F. Shepherd. The Shepherd patent shows a pair of blocks with complementary faces resiliently held together. The device has different sized apertures through one side into which two different sized hooks may be inserted. When the hooks are inserted, the eyes can be manually aligned transversely across a narrow passageway through which the leader can be threaded. The narrow passageway for the leader has a flared cone-shaped outer end into which the leader is initially inserted. The cone-shaped outer portion of the aperture through which the leader is inserted accomplishes one of the desired objectives of a fishhook threader in that it guides the leader through the eye of the hook.
There are several drawbacks to the Shepherd device. First of all, there are only two openings through which different sized fishhooks may be inserted. If the fishhooks are larger than the openings, they cannot be threaded using this device. If the hooks are very much smaller than the opening, they will be so loosely held in the apertures that it will be necessary to hold the hook in its proper position with an extra hand in order to get the leader threaded through it.
There is no provision in the Shepherd device for clearing the eye of the fishhook of any lacquer which may be blocking it. Another disadvantage is that to actually tie the knot in the leader to affix the leader to the fishhook, the leader and the hook must be removed from the device by separating the two blocks. In the Shepherd device, the eye of the fishhook must be accurately aligned across the leader aperture by hand. The Shepherd device has no positive clamping mechanism to hold the eye of the hook in its aligned positioned across the leader path.
A second device for threading fishhooks is shown in U.S. Pat. No. 2,783,571 to Stilwell, In the Stilwell device, a fishhook is held in a slot through the use of permanent magnets. A pair of permanent magnets at each edge of the fishhook slot are intended to hold the eye of a fishhook across a tapered slot through which the leader can be inserted. While this device guides the leader through the eye of the fishhook, there is no positive locking mechanism which holds the eye of the fishhook accurately across the leader opening. If the fishhook or the device is jarred during the threading process, the hook can move within the device and the eye will no longer br properly lined up with the leader threading aperture. There is nothing which accurately centers the eye of the hook across the tapered slot. In addition, the Stilwell device does not show anything to ensure that the eye of the hook is clear of lacquer or other material prior to threading it. There is also no way to form an easily tied knot, such as a stevedore's knot, without removing the fly and the leader from the device.
None of the prior art fishhook threaders have means for accurate alignment and centering of the eye of the fishhook across the opening through which the leader is guided so as to allow the leader to pass through the eye of the fishook without requiring fine manual dexterity.